Current-limiting type vehicle-mounted electric appliance surge protection circuit
By introducing current limiting circuits and voltage stabilization circuits into surge protection circuits, the problems of excessive low-position operating voltage limit and insufficient load current capacity in the prior art are solved, and a wider operating voltage range and larger loads are achieved Current capability.
Patent Information
- Application Number
- CN202421041791.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-14
- Publication Date
- 2025-02-18
- Estimated Expiration
- 2034-05-14
AI Technical Summary
The existing surge protection circuit has too high limits in terms of low-position operating voltage and insufficient load current capacity, which cannot meet the requirements of some customers.
A current limiting vehicle electrical surge protection circuit is designed, and the current limiting circuit and voltage stabilization circuit are formed by introducing the first diode D1, the second diode D2, the MOS tube Q1 and the resistors R1 and R2 to form the current limiting circuit and the voltage stabilization circuit to achieve the Effective suppression of surge voltage.
The operating voltage range is increased, the low-position operating voltage limit is reduced, the load current capacity is increased, and the on-resistance is constant, which helps to suppress conduction emissions.
Smart Images
Figure CN222508788U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of automobile electronics industry, and more specifically, to a current limiting type vehicle-mounted electrical appliance surge protection circuit. Background Art
[0002] The existing surge protection circuit is as follows Figure 1 As shown in the utility model CN 218482659 U, the circuit has the following problems:
[0003] 1. Regardless of whether surge voltage occurs, Q1 works in a linear amplification state, so its voltage drop is large (2V~3V), which leads to a narrower operating voltage range of electronic control products and a low operating voltage that is too high, which cannot meet the requirements of some customers.
[0004] 2. Due to the large voltage drop of Q1, the heat dissipation capacity of its package limits the load current capability of the circuit, which usually does not exceed 200mA. Summary of the invention
[0005] To this end, the utility model provides a current limiting type vehicle-mounted electrical appliance surge protection circuit to solve the technical problems mentioned in the background technology that the low-level operating voltage limit is too high and the rated load current is too small.
[0006] The technical solution of the utility model is as follows: a current limiting vehicle electrical appliance surge protection circuit, characterized in that it includes: a voltage input end, a voltage output end, a first resistor R1, a first diode D1, a second diode D2, a MOS tube Q1 and a second resistor R2, the cathode of the first diode D1 and one end of the first resistor R1 are connected to the voltage input end, the anode of the first diode D1 is connected to one end of the second resistor R2 and the gate of the MOS tube Q1, the other end of the first resistor R1 is connected to the source of the MOS tube Q1, the other end of the second resistor R2 is connected to one end of the second diode D2 and the signal ground, and the other end of the second diode D2 is connected to the drain of the MOS tube Q1 and the voltage output end.
[0007] Furthermore, the first diode D1 is a voltage regulator.
[0008] Furthermore, the MOS tube Q1 is a PMOS tube.
[0009] Furthermore, the second diode D2 is a transient voltage suppression diode.
[0010] Beneficial effects of the utility model:
[0011] 1. Wide operating voltage range.
[0012] In the prior art, regardless of whether a surge voltage occurs, Q1 operates in a linear amplification state, so its voltage drop is relatively large (2V to 3V), resulting in a narrower operating voltage range for electronic control products and an excessively high low-level operating voltage. In the present invention, Q1 is in an on state, with a voltage drop of approximately 200mV. Adding the voltage drop of the current limiting resistor, it is also easily controlled within 1V, and the low-level operating voltage limit can be increased by approximately 2V.
[0013] 2. Large load current capacity.
[0014] In the prior art, the typical load current is about 200 mA; while the load current of the present invention can be designed to be 500 mA.
[0015] 3. The on-resistance is constant, which is more conducive to the suppression of conducted emissions along the power line.
[0016] In the prior art, Q1 is in an amplification state, and its on-resistance changes with the load current, so the suppression of conducted emission also changes; while the on-resistance of the utility model is constant, and the suppression of conducted emission along the power line is relatively stable. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 It is a schematic diagram of the structure of a surge protection circuit in the prior art.
[0018] Figure 2 It is a structural schematic diagram of the utility model. DETAILED DESCRIPTION
[0019] In order to enable those skilled in the art to better understand the solution of the utility model, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. The described embodiment is only a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the utility model.
[0020] In an embodiment of the present utility model, Figure 2 It is a structural schematic diagram provided according to the specific structure of the utility model, such as Figure 2As shown, the utility model includes: a voltage input end, a voltage output end, a first resistor R1, a first diode D1, a second diode D2, a MOS tube Q1 and a second resistor R2, wherein the cathode of the first diode D1 and one end of the first resistor R1 are connected to the voltage input end, the anode of the first diode D1 is connected to one end of the second resistor R2 and the gate of the MOS tube Q1, the other end of the first resistor R1 is connected to the source of the MOS tube Q1, the other end of the second resistor R2 is connected to one end of the second diode D2 and the signal ground, and the other end of the second diode D2 is connected to the drain of the MOS tube Q1 and the voltage output end.
[0021] Specifically, the first diode D1 is a voltage regulator.
[0022] Specifically, the MOS tube Q1 is a PMOS tube.
[0023] Specifically, the second diode D2 is a transient voltage suppression diode.
[0024] The structure of the utility model is as follows Figure 2 The first diode D1, the first resistor R1, the second resistor R2 and the MOS tube Q1 form a current limiting circuit, and the second diode D2 forms a voltage stabilizing circuit. The combination of the two can suppress the P5 pulse surge voltage in the automotive electrical environment.
[0025] The working principle of the utility model is as follows, wherein:
[0026] V in is the surge voltage input.
[0027] V out It is the output voltage after being protected by this device.
[0028] R1 is a current-sense resistor that provides negative feedback to the PMOS control signal.
[0029] D1 is a low-power voltage regulator tube, which is used to stabilize the control signal input of Q1.
[0030] D2 is a transient voltage suppressor diode, which is used to limit the voltage.
[0031] The following parameters represent:
[0032] V GS : Control electrode voltage of PMOS tube.
[0033] V GS(Plateau) : Miller platform voltage of PMOS tube control pole.
[0034] V Z(D1) : Rated stable voltage of Zener diode D1.
[0035] ILOAD : Load current of the circuit.
[0036] In this circuit:
[0037] V Z(D1) =V GS +R1*I LOAD
[0038] Thus:
[0039] V GS =V Z(D1) -R1*I LOAD
[0040] When the surge voltage is applied, I LOAD Will increase, V GS will decrease when it reaches V GS(Plateau) When the voltage is close to the MOSFET, the MOS tube Q1 enters the amplification state from the conduction state. Limited by the back-end TVS clamping effect, the MOS tube Q1 bears the main voltage difference of the surge voltage.
[0041] The energy of the surge voltage loaded on the MOS tube is:
[0042] (V IN –V OUT )*I LOAD
[0043] Because I LOAD Smaller (less than 1A), about 5% of the surge current (typical value 20A) that a single TVS solution can withstand, which reduces heat generation and makes it easier to pass the P5 pulse surge test.
[0044] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to examples, ordinary technicians in the field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.
Claims
1. A current limiting type vehicle-mounted electrical appliance surge protection circuit, characterized in that: include: A voltage input terminal, a voltage output terminal, a first resistor R1, a first diode D1, a second diode D2, a MOS transistor Q1 and a second resistor R2, wherein the cathode of the first diode D1 and one end of the first resistor R1 are connected to the voltage input terminal, the anode of the first diode D1 is connected to one end of the second resistor R2 and the gate of the MOS transistor Q1, the other end of the first resistor R1 is connected to the source of the MOS transistor Q1, the other end of the second resistor R2 is connected to one end of the second diode D2 and the signal ground, and the other end of the second diode D2 is connected to the drain of the MOS transistor Q1 and the voltage output terminal.
2. The current limiting type vehicle-mounted electrical appliance surge protection circuit according to claim 1, characterized in that: The first diode D1 is a voltage regulator.
3. The current limiting type vehicle-mounted electrical appliance surge protection circuit according to claim 1, characterized in that: The MOS tube Q1 is a PMOS tube.
4. The current limiting type vehicle-mounted electrical appliance surge protection circuit according to claim 1, characterized in that: The second diode D2 is a transient voltage suppressor diode.